A motor is an electromechanical device which converts electrical energy, delivered in the form of voltages or currents, into mechanical energy that is represented as rotational movement. The electromechanical force is described by the Lorentz force law. A motor includes a stator and a rotor. The stator typically includes a wire coil having a number of windings that receive a driver current.
The rotor typically includes a series permanent magnets. The rotor and stator are mechanically arranged such that the rotor can move freely with respect to the fixed stator. Electromagnetic interaction, or an electromagnetic flux exists between the stator and rotor. The rotor rotates because the stator winding and the magnetic field are arranged so a mechanical force, or torque is developed around the rotor axis. This causes the rotor to move for each polarity change in the stator windings. A generator, or dynamo may be constructed in a similar fashion.
The rotor assembly typically is made from a number of electromagnets spaced about a shaft. Typically, the magnets are contained in slots formed on the shaft, such as, the rotor disclosed in U.S. Pat. No. 5,554,900 to Pop, Sr., which is herein incorporated by reference in its entirety. Then, the rotor assembly is rotatably supported mechanically within the stator housing by low friction bearings, in a so called “in-runner” configuration.
Often, to support the magnets, these slots that receive the magnets are detrimental. The slots house the magnets, which are spaced far from the windings in operation. This excessive spacing or gap lessens or reduces the electromagnetic flux between the permanent magnets and the stator windings.
Moreover, it is costly to manufacture a rotor having a number of slots. Tight tolerances between the rotor and the magnets must be ensured so that the permanent magnets are properly supported in the slots, and will stay stationary relative to the rotor shaft during fast rotation of the rotor.